1. Field of the Invention
This invention relates in general to unassembled prefabricated door units for use in the construction industry. More particularly, this invention relates to a jig for facilitating the assembly of the door unit from its unassembled components.
2. Description of the Prior Art
The construction industry has turned increasingly to the use of prefabricated building units. Such units are used to minimize the cost of building a house or other structure by decreasing the amount of labor required by skilled craftsmen, such carpenters. More particularly, while it was once the custom for a carpenter to completely make a door frame from raw materials on hand at the job site and to the hang the door in the door frame, the high wage scale for carpenters has largely made such an operation prohibitively expensive. Thus, the use of various prefabricated door units is now widespread.
Two major types of prefabricated door units are generally in use. The first type is that which is known as a "pre-hung" door. In such a door unit, the entire door frame is assembled at the factory with the door being hung inside the frame. All that is required at the job site is for the door frame with the attached door to simply be fitted into and secured in a rough opening for the door already provided in the building.
Another type of prefabricated door unit is that which may be referred to as an unassembled door unit. One example of such a door unit is that which is known as the Boxer door unit manufactured by Interior Wood Products, Inc. of Saint Paul, Minnesota. In this type of door unit, all of the components of the door frame including any necessary moldings are pre-cut and pre-machined, but are not pre-assembled, at the factory. Such a door unit requires that the door frame be assembled at the job site and then placed into the rough opening in the building. Since all the components of the door unit are pre-cut, considerable labor savings are achieved since a carpenter need only assemble, but not fabricate, the door unit components.
A major disadvantage of a pre-hung door unit as opposed to an unassembled one is that the pre-hung unit is quite a bit more bulky and thus harder to hold and manipulate. The increased size of the pre-hung door unit can increase shipping costs by decreasing the number of door units which can be shipped in any given sized vehicle. In addition, because delivery men sometimes find pre-hung units hard to handle, it often occurs that such units are damaged upon delivery by dropping them while unloading. This damage causes construction delays since a new door unit must be ordered from the factory or distributor. In some cases, the delay might be quite long which often annoys the customer for whom the building is being constructed.
An unassembled door unit, such as the Boxer unit referred to previously, has a number of advantages over the pre-hung unit. First, unassembled door units can be shipped in smaller boxes since the unassembled components of the door frame and the like can be packed tighty into the box. In addition, because the shipping box is smaller, unassembled door units may be more easily handled and unloaded, thereby decreasing the chance of damaging such units. However, up until this invention, unassembled door units have customarily been sold and used without any sort of assembly jig or the like. Each user has had to find his own method of assembling the components of the door unit by hand without the aid of a jig. Such manual assembly required the user to somehow align the components of the door frame while simultaneously trying to affix them together. The difficulty associated with such an assembly operation has been a deterrent to increased utilization of unassembled door units.
While some jigs are known in the building industry for use in assembling doors and other building components, these jigs are generally only suitable for factory use. For example, most of these jigs comprise steel tables and the like which have various powered mechanisms for holding, supporting and guiding the door components being assembled. Such jigs are quite expensive and cost on the order of $300-$500. Such a large expense is not justified for the occasional unassembled door units that a small scale user, such as a small home builder or home owner, might wish to assemble.